MN-500 "disappearing"

There are just a couple of web sites that consistently cause this
issue. If I avoid them, I never have issues, but
it is like clock work, I go to one of them and if I "stay long enough",
I get the following error:

"The connection was refused when attempting to contact www.____.com."

Once this error is received, it stays until I reboot - no matter what
site I go to, it says it can't get there.

When I go to "Start | Settings | Network Connections" I noticed that in
my Network Connections, that my
"Internet Gateway" entry goes away and all I'm left with is my LAN or
High-Speed Interent section that
correctly shows my Local Area Connection, oddly enough to my MS
basestation, which as I stated, is no
longer listed under the Internet Gateway section. Interestingly, I
"repaired" my LAN entry, and that allowed me to
log into my pop3 email account, which obviously used the gateway
(mn-500) to get there. But still no internet and
again, still not "Internet Gateway" section or the MN-500 listed in it.

So for some reason going to a few particular sites (for example
www.chickenbucket.com or www.trektoday.com/),
causes the gateway to go away. I reboot, it shows back up and
everything is OK.

So I have a few questions:
1) Does anyone know why a specific website would suddenly cause the
MN-500 entry in the "Internet Gateway" section
to vanish, in effect disabling my interenet connect?
2) What is an easier way to get it to show back up instead of
rebooting? Pulling the power cable?